1. Field of the Invention
The present invention is directed generally to computer readable media, apparatuses, systems, and methods that concern image guided medical procedures.
2. Description of Related Art
Image guided surgery (IGS), also known as image guided intervention (IGI), has become an established and proven technology field that enhances a physician's understanding of the location of his instruments within anatomy during therapy delivery. IGI has grown to include 2-dimensional (2-D) and 3-dimensional (3-D) applications. Virtual fluoroscopy as described in U.S. Pat. No. 6,470,207, Navigational Guidance via Computer Assisted Fluoroscopic Imaging, Simon et al., which is expressly incorporated by reference, discloses how to register the coordinate system of anatomy in a live operating theatre to that of a 2-D fluoroscopic image and then superimpose the real-time movements of instruments on that image as icons. U.S. Pat. No. 6,490,467, Surgical Navigation Systems Including Reference and Localization Frames, Bucholz et al., which is also expressly incorporated by reference, discloses how to register the coordinate system of anatomy in a live operating theatre to that of a 3-D magnetic resonance imaging (MRI) or computed tomography (CT) image volume and then superimpose the real-time movements of instruments on that image volume as icons. The techniques disclosed in these patents combined with other state of the art technologies have worked well in procedures involving static anatomy. Static anatomy is anatomy that does not move or has very minimal movement with respect to heart beat and respiration, such as the sinuses, long bones, brain, and individual vertebral bodies of the spine. The use of image guidance is fast approaching the standard of care in neurosurgical tumor resection, spinal implant placement, ear-nose-and-throat (ENT) surgery, and orthopedics.
However, IGI has not made significant inroads into medical procedures involving dynamic anatomy. Dynamic anatomy is anatomy that moves significantly with respect to heart beat and respiration, such as the heart, lungs, kidneys, liver, and blood vessels. IGI to date is limited mostly to use in static anatomy medical procedures primarily due to its usage of static imaging modalities such as single frame fluoroscopy, and single volume MRI and CT.
Imaging modalities do exist to capture dynamic anatomy. Modalities such as electrocardiogram (ECG)-gated MRI, ECG-gated CT and cinematography (CINE) fluoroscopy (e.g., looped CINE fluoroscopy) are readily available in hospitals worldwide. These dynamic imaging modalities can capture anatomy over an entire periodic cycle of movement by sampling the anatomy at several instances during its characteristic movement and then creating a set of image frames or volumes. The use of dynamic imaging modalities in IGI will allow IGI to transcend the boundaries of static anatomy and administer efficacy benefits to even more medical procedures.
U.S. Pat. No. 6,473,635, A Method of and Device for Determining the Position of A Medical Instrument, Rasche, which is expressly incorporated by reference, proposes using the ECG waveform emanating from a live patient in the operating theatre to continuously select from a set of images that were gated to ECG data. However, Rasche's proposal will not work when the patient exhibits an irregular ECG pattern due to the medical therapies that are being applied to him. Examples of induced ECG irregularity would occur during pacemaker and implantable cardioverter defibrillator lead placement and radiofrequency ablation of myocytes to cure tachycardia.